He is also a vehement critic of U.S. drone attacks on his country, vowing to order them shot down if he is prime minister and leading an anti-drone protest march last month.

On Saturday, Khan boarded a flight from Canada to New York in order to appear at a fundraising lunch and other events. But before the flight could take off, U.S. immigration officials removed him from the plane and detained him for two hours, causing him to miss the flight.

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On Twitter, Khan reported that he was "interrogated on [his] views on drones" and then added: "My stance is known. Drone attacks must stop." He then defiantly noted: "Missed flight and sad to miss the fundraising lunch in NY but nothing will change my stance."Read more: Press TV